Filling out Northern Spain Itinerary

I would take Euskotren to travel from Bilbao to San Sebastian. - http://www.euskotren.eus

There's more to do in Bilbao than the Guggenheim, and it has a larger and less touristy historic quarter than San Sebastian.

I liked Vitoria-Gasteiz and Hondarribia. The latter is east of SS, practically on the French border. Buses from SS. If you make it to V-G and have a car, it will be relatively easy to get to the atmospheric hill town of Laguardia, which is near the La Rioja area. It has some wine bars. There's bus service from V-G, but on a short trip I wouldn't have the patience for that.

The three little coastal towns (fishing villages turned touristy) of Zarautz, Getaria and Zumaia make for a pleasant day, but I haven't been to Llanes; they might be more of the same. They're west of SS. You can get to them all by bus and/or train.

Leon has a large, lively historic area full of bars and restaurants, plus the magnificent glass in the cathedral. There's a Gaudi building. It's a very attractive destination and is likely to be warmer and sunnier than your previous stops

Gijon is a bit more understated in its charms, though it has some interesting early 20th century architecture to go along with its small historic district. I read that Gijon is where residents of Oviedo go to have fun. Gijon would mean a considerably longer train trip to Madrid, however.

Another possibility, though I haven't checked driving times, would be the Picos de Europa area. The scenery is very dranatic--even prettier than the Basque country. Potes is a very nice old stone town. Difficult to get there without a car, so this vwould be a good opportunity to see it.

Edited to add: The Euskotrn route between Bilbao and SS is very scenic, but it takes much longer than the bus. I can't recommend it when there's so much of Bilbao itself being skipped.

Some ideas ...

Day 1: Arrive Bilbao at 8:45. Bus to Bilbao bus station, drop luggage, tour Guggenheim, then bus to San Sebatian.
Day 2: San Sebastian
Day 3: San Sebastian
Day 4: Drive to Vitoria-Gasteiz, or LaGuardia (Rioja), or Santillana del Mar
Day 5: Drive to Llanes for Fiesta of Maria Guia
Day 6: Llanes
Day 7: Drive to Oviedo, or thru Picos de Europa to Leon
Day 8: Return car, train to Madrid
Day 9: Madrid
Day 10: Madrid
Day 11: Fly home

Or spend your first night in Bilbao ...

Day 1: Arrive Bilbao at 8:45. Tour Guggenheim. Stay in Bilbao (1N)
Day 2: Bus to San Sebastián (3N)
Day 3: San Sebastian
Day 4: Day trip to Hondarribia
Day 5: Drive to Llanes for Fiesta of Maria Guia

I already have non-refundable hotel in San Sebastian, so that part isn't changeable.

I know I'm giving Bilbao short shrift, but there are cheap flights from Stuttgart to Bilbao so I'm hoping we can return and do part of the Camino on a future trip. I know San Sebastian is touristy and relatively pricey, but weather agreeing it's my beachy part of the trip (hotel is 3 minutes from beach).

Thanks for the recs, looking into all the suggestions! Keeping them coming!

What do you guys think about this itinerary?

Day 1: Fly to Bilbao, Guggenheim, bus to San Sebastian

Day 2: San Sebastian

Day 3: San Sebastian

Day 4: Drive to Guernica, continue on to Mundaka for lunch and surf-watching, visit SAN JUAN DE GAZTELUGATXE afterwards, continue to Bilbao, night in Bilbao.

Day 5: Drive to San Vicente de la Barquera for lunch, then check into hotel near Llanes and go to festival.

Day 6: Festival and/or villages of Picos de Europa, night in Llanes

Day 7: Drive to Oviedo, drop of car, night in Ovideo

Day 8: Train to Madrid

Day 9: Madrid

Day 10: Madrid

Day 11: Fly home

This gives us a late afternoon/evening in Bilbao to enjoy the old quarter/food scene, cuts down on some driving distance, seems to give us an interesting "mix" of types of sights. Anyone want to weigh in? Also still considering Leon over Oviedo, anyone have an argument for either city?

And I just realized that I have two nights inbetween San Sebastian and Llanes. Whoops! So we're planning one night in Bilbao to see the city aside from the Guggenheim and then am unsure where to stay between there and Llanes. I made a new post, though. We'll be driving to Leon after Llanes for one night.